<html>
<body>
<script>
async function fetchJson() {
  let r = await fetch(`http://${location.hostname}:3000/`)
  return r.json()
}
async function showFetch() {
  let json = await fetchJson()
  document.getElementById('json1').innerHTML = json
} 
</script>
<button onclick="fetchJson()"></button>
<pre id="json1">
</pre>
</body>
</html>